Not Applicable
Not Applicable
1. Field of the Invention
The present invention relates to suspension systems for vehicles which include trailers as well as cars and trucks, and more particularly to a combination air bag and torsion axle suspension system.
2. Description of the Related Art
Torsion axles have been known for many years, for example as shown in U.S. Pat. Nos. 2,998,981 to Derr and 3,353,840 to Love. Torsion axles have proven to be extremely popular primarily because if one wheel hits a bump or rut, it can react independently of the other wheel, which may not have hit a bump or rut at the exact same time. This torsion axle concept therefore operates to keep a trailer or the like moving as straight as possible behind a towing vehicle and absorbs some of the shock of the road over which it is passing with an independent suspension. This can be contrasted with a straight axle situation where if one wheel were to drop into a rut or the like and be slowed down for that reason while the wheel on the other side of the trailer did not have the same experience at the same time, the trailer would tend to turn somewhat to allow the wheel that is on the flat part of the road to move forward while the wheel that is in the rut would be restrained, therefore causing the axle to be not perpendicular with the direction of towing of the vehicle itself, assuming in this example that the trailer was being towed on a straight portion of the road.
Besides the two aforementioned torsion axles which are constructed of a square axle in cross section with elongated rubber members all disposed within a larger tube, another patent, U.S. Pat. No. 5,161,814 to Walker, also discloses a newer patent using a similar construction. One of the most common and popular torsion axles is a TorFlex(copyright) rubber torsion suspension system by Dexter Axle. This last mentioned torsion axle has independent and separate stub axles on each side to enhance the independent aspect of such an axle.
Torsion axles can be constructed differently as evidenced by U.S. Pat. No. 5,163,701 to Cromley, Jr. which uses a plurality of elongated bars which can twist and bend but return to their original position after such bending. In contrast, it has been well known for many years to use air bags for straight, non-torsion axles, such as shown in U.S. Pat. Nos. 3,784,221 to Frasier and 5,427,404 to Stephens. While it is true that both the torsion axle technology and the air bag technology has been quite successful independently in making a smoother ride and enhanced the handling performances of vehicles having such suspension systems, these suspension systems still have their shortcomings and there is a need for improvement thereto.
The present invention relates to a vehicle suspension system assembly for attachment to a vehicle frame having a torsion axle and at least two ground engaging wheels operatively rotatably attached to each respective end of the torsion axle. An attachment member is adapted to be attached to the frame and an arm is operably pivotally attached to the attachment member along an axis. A torsion axle is received in a torsion axle receiving portion of the assembly at a first distance spaced from the aforementioned axis for selectively receiving the torsion axle. An air bag is operatively disposed between the frame and the arm, the air bag being spaced at a second distance from the axis. A linkage element of variable length, which can be a shock absorber, is operably attached to the frame and to the arm whereby the arm will be biased to a predetermined position with respect to the frame and yet allow the arm to pivot about the axis. In a preferred embodiment, the air bag is spaced further away from the pivotal axis of the arm than is the torsion axle.
An object of the present invention is to provide an improved vehicle suspension system.
Another object of the present invention is to provide a combination air bag and torsion axle suspension system.